http://www.ck12.org Chapter 23. Feynman Diagrams
- Here are two particles colliding! Watch out!
- We use the following symbols in Feynman diagrams:
- Annihilation Diagram: When matter and antimatter particles collide, they annihilate, leaving behind pure
energy for the example below in the form of electromagnetic radiation (photons!). A different set of matter
and antimatter is recreated soon thereafter. The Feynman diagram for that process looks like this:
Note that space and time axes have been left out; they are understood to be there. Also note that the arrow on the
bottom is supposed to be backwards. We do that any time we have an antiparticle. Most people like to think of
antiparticles as traveling backwards in time, and this is roughly explained by CPT symmetry.
It isveryimportant that you remember that time is the horizontal axis! A lot of people see the drawing above and
think of it as two particles coming together at an angle. These two particles are in a collision but the angle is not
known from this diagram, because only one dimension of space is graphed.